Detection and Quantitation of Cyclodextrins

ABSTRACT

The invention relates to the detection and quantitation of cyclodextrins and cyclodextrin derivatives in solutions comprising a protein. The invention further relates to methods of evaluating pharmaceutical preparations for the presence of residual cyclodextrins.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the detection and quantitation of cyclodextrinsand cyclodextrin derivatives in solutions comprising a protein. Theinvention further relates to methods of evaluating pharmaceuticalpreparations for the presence of residual cyclodextrins.

2. Background

Cyclodextrins are cyclic polysaccharides most commonly consisting of six(α-cyclodextrin), seven (β-cyclodextrin), or eight (γ-cyclodextrin)glucose units linked by alpha-1,4-glucosidic bonds in a donut shapedring. As a consequence of the chair formation of the sugar units, allsecondary hydroxyl units are located on one side of the ring, while allof the primary hydroxyl groups are situated on the other side. As aresult, the external faces are hydrophilic, making the cyclodextrinswater-soluble. In contrast, the cavities of the cyclodextrins arehydrophobic, since they are lined by the hydrogens of atoms C₃ and C₅and by ether-like oxygens. This structure allows cyclodextrins to forminclusion complexes with hydrophobic compounds. Based on thischaracteristic, cyclodextrins are widely used to increase the solubilityof poorly water soluble pharmaceuticals, enhance pharmaceuticalstability, and reduce unwanted side effects of pharmaceuticals.

The hydroxyl groups of cyclodextrins may be derivatized to alter thecharacteristics of the molecule (e.g., water solubility, bindingspecificity). Methyl-β-cyclodextrin (MBCD) is one of the most frequentlyused cyclodextrin derivatives.

Cyclodextrins are also used in cell culture systems to carry hydrophobicnutrients, such as cholesterol, into cells. Cyclodextrins areparticularly useful for the culturing of cholesterol auxotrophic cells,e.g., cholesterol auxotrophic CHO cells, COS cells, and NSO cells. Whencell cultures are used to produce naturally occurring or recombinantproteins, particularly therapeutic proteins, the presence ofcyclodextrins as a residual contaminant in the purified protein productis an issue in the production of pharmaceutical products. Thus, asensitive and rapid technique for the detection and quantification oflow levels of cyclodextrins or cyclodextrin derivatives in a solutioncomprising a protein is needed.

Grosse et al. (J. Chromatography B 694:219 (1997)) disclose a techniquefor detecting MBCD using size exclusion chromatography in the presenceof a fluorophore (1-naphthol) that forms an inclusion complex with MBCDand allows fluorescent detection of the inclusion complex. Thistechnique, which was designed for the detection of MBCD in plasmasamples for pharmacokinetic studies, requires extraction of samples withorganic solvents, evaporation, and dissolution of the residue in themobile phase prior to chromatography. Gage et al. (J. Pharm. Biomed.Analysis 22773 (2000)) disclose a similar technique using 1-naphthol formeasuring the presence of sulphobutylether-β-cyclodextrin in plasmasamples. This method requires processing of the sample, including solidphase extraction, evaporation, and dissolution of the residue, prior tochromatography. These techniques do not achieve separation ofcyclodextrins from protein components.

A need exists in the art for a method of testing for the presence ofcyclodextrin or cyclodextrin derivatives in the presence of a protein,preferably without the need for sample extraction steps.

SUMMARY OF THE INVENTION

Accordingly, in one aspect, the invention provides a method for testingfor the presence of a cyclodextrin or cyclodextrin derivative in asolution comprising a protein, the method comprising separating anycyclodextrin or cyclodextrin derivative that may be present from saidprotein by size exclusion chromatography (SEC), contacting saidcyclodextrin or cyclodextrin derivative with an agent that forms adetectable inclusion complex with a separated cyclodextrin orcyclodextrin derivative, and measuring for the presence of a signal fromsaid inclusion complex.

Another aspect of the invention is a method for determining the quantityof a cyclodextrin or cyclodextrin derivative that may be present in asolution comprising a protein, the method comprising separating anycyclodextrin or cyclodextrin derivative from said protein by SEC,contacting said cyclodextrin or cyclodextrin derivative with an agentthat forms a detectable inclusion complex with a separated cyclodextrinor cyclodextrin derivative, measuring for the presence of a signal fromsaid inclusion complex, and determining the size of said signal, whereinthe size of the signal is indicative of the quantity of the cyclodextrinor cyclodextrin derivative in the solution.

A third aspect of the invention is a method of evaluating apharmaceutical preparation, the method comprising:

(a) providing a pharmaceutical preparation comprising a therapeuticprotein and a pharmaceutically acceptable carrier;(b) separating said pharmaceutical preparation by SEC;(c) contacting any cyclodextrin or cyclodextrin derivative that may bepresent in the pharmaceutical preparation with an agent that forms adetectable inclusion complex with a separated cyclodextrin orcyclodextrin derivative; and(d) detecting a signal from said inclusion complex, wherein the size ofthe signal is indicative of the quantity of the cyclodextrin orcyclodextrin derivative in the preparation.

In one embodiment of the invention the cyclodextrin or cyclodextrinderivative is MBCD.

In another embodiment of the invention the agent is a fluorophore, e.g.,1-naphthol. The agent may be brought in contact with the cyclodextrin orcyclodextrin derivative prior to, during, or after the separation bySEC.

In one embodiment a sample of the solution or the pharmaceuticalpreparation is loaded on the SEC column without any preparation, e.g.,the sample is not extracted with organic solvents, dried, resuspended,concentrated, or otherwise altered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows representative chromatograms for a pharmaceuticalpreparation of purified natilizumab with and without MBCD. (a)pharmaceutical preparation (19.6 mg/ml, natilizumab); (b) formulationbuffer; (c) pharmaceutical preparation (19.6 mg/mL natilizumab) spikedwith 1.3 μg/mL MBCD.

FIG. 2 shows the linearity curve for the MBCD standards.

FIG. 3 shows the linearity curve for a pharmaceutical preparation ofnatilizumab spiked with MBCD.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the detection and quantitation of lowlevels of a cyclodextrin or a cyclodextrin derivative in a solutioncomprising a protein. In one embodiment, the methods of the inventionare useful for the evaluation of purified proteins prepared from cellsgrown in the presence of a cyclodextrin or a cyclodextrin derivative forthe presence of residual cyclodextrin. Accordingly, in one aspect, theinvention provides a method for testing for the presence of acyclodextrin or cyclodextrin derivative in a solution comprising aprotein, the method comprising separating any cyclodextrin orcyclodextrin derivative that may be present from said protein by sizeexclusion chromatography (SEC), contacting said cyclodextrin orcyclodextrin derivative with an agent that forms a detectable inclusioncomplex with a separated cyclodextrin or cyclodextrin derivative, andmeasuring for the presence of a signal from said inclusion complex.

Another aspect of the invention is a method for determining the quantityof a cyclodextrin or cyclodextrin derivative that may be present in asolution comprising a protein, the method comprising separating anycyclodextrin or cyclodextrin derivative from said protein by SEC,contacting said cyclodextrin or cyclodextrin derivative with an agentthat forms a detectable inclusion complex with a separated cyclodextrinor cyclodextrin derivative, measuring for the presence of a signal fromsaid inclusion complex, and determining the size of said signal, whereinthe size of the signal is indicative of the quantity of the cyclodextrinor cyclodextrin derivative in the solution.

A third aspect of the invention is a method of evaluating apharmaceutical preparation, the method comprising:

(a) providing a pharmaceutical preparation comprising a therapeuticprotein and a pharmaceutically acceptable carrier;(b) separating said pharmaceutical preparation by SEC;(c) contacting any cyclodextrin or cyclodextrin derivative that may bepresent in the pharmaceutical preparation with an agent that forms adetectable inclusion complex with a separated cyclodextrin orcyclodextrin derivative; and(d) detecting a signal from said inclusion complex, wherein the size ofthe signal is indicative of the quantity of the cyclodextrin orcyclodextrin derivative in the preparation.

The term “cyclodextrin or cyclodextrin derivative,” as used herein,refers to any known cyclodextrin, particularly α-cyclodextrin,β-cyclodextrin, and γ-cyclodextrin, and any known cyclodextrinderivative. Cyclodextrin derivatives are disclosed in U.S. Pat. Nos.3,426,011, 3,453,257, 3,453,258, 3,453,259, 3,453,260, 3,459,731,3,553,191, 3,565,887, 4,383,992, 4,535,152, 4,616,008, 4,638,058,4,659,696, 4,746,734, 4,678,598, 5,594,125, 5,710,268, and 5,831,081,each of which is incorporated by reference. Examples of cyclodextrinderivatives include MBCD, hydroxyethyl-β-cyclodextrin, andhydroxypropyl-β-cyclodextrin. Cyclodextrins and cyclodextrin derivativesare available from American Maize Products Company, Wacker Chemicals(USA), Inc., and Sigma-Aldrich Chemical Company.

The term “agent that can form a detectable inclusion complex with acyclodextrin or a cyclodextrin derivative,” as used herein, refers toany agent that is capable of forming an inclusion complex with acyclodextrin or a cyclodextrin derivative, wherein the inclusion complexis capable of detection upon elution from a SEC column. The termincludes agents that are not inherently detectable but contain adetectable label, e.g., a radionuclide or a fluorescent tag. The termalso includes agents that are not inherently detectable but form adetectable inclusion complex with a cyclodextrin or cyclodextrinderivative. Examples of methods of detection include, but are notlimited to, fluorescent detection, ultraviolet detection, radiometricdetection, colorimetric detection, fluorescence polarization,evaporative light-scattering, capillary electrophoresis, infraredspectroscopy, ¹H NMR, and mass spectroscopy. In one embodiment thedetectable agent is a fluorophore, e.g., 1-naphthol. Other detectableagents, such as phenolphthalein and 8-anilinonaphthalene-1-sulfonicacid, may be used as well.

The term “therapeutic protein,” as used herein, refers to any peptide orprotein that is known to be useful for the prevention, treatment, oramelioration of a disease or disorder, e.g., an antibody, growth factor,cell surface receptor, cytokine, hormone, toxin, or fragments and/orfusion proteins of any of the foregoing. The term “antibody” is used inits broadest sense to include monoclonal antibodies, chimeric,humanized, or fully human antibodies, and antigen-binding antibodyfragments and/or derivatives thereof, such as single chain antibodies,light chain and heavy chain dimers, and Fv, Fab, and (Fab′)₂ fragments.Examples of therapeutic proteins include, but are not limited to,proteins such as erythropoietin, growth hormone, colony stimulatingfactor, insulin, and therapeutic antibodies such as natilizumab,infliximab, adalimumab, MabThera, Herceptin, Palivizumab, Abciximab,Alemtuzumab, OKT3-muromonab-CD3, Basiliximab, Gemtuzumab ozogamicin,Omalizumab, Ibritumomab tiuxetan, Edrecolomab-Mab17-1A, Tositumomab,efalizumab, bevacizumab, and cetuximab. The protein may be isolated fromcells in which it is naturally occurring or cells that have beengenetically engineered to express it, e.g., recombinantly expressed.

The terms “at least 90% (or higher) pure” and “at least 90% (or higher)homogeneity,” as used herein, refer to a protein that has been purifiedaway from other proteins, lipids, nucleic acids and other cellularcomponents such that the protein makes up at least 90% (or higher) bydry weight of the purified preparation. In some embodiments, a proteinmay be at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% pure.

The term “derivative thereof,” as used to refer to a cell line describedherein, refers to any cells created from that cell line that have atleast one new characteristic. Examples of cell derivatives having a newcharacteristic include, but are not limited to, cells having a differentgrowth pattern (e.g., cholesterol auxotrophy) such as can be generatedby selective pressure, and cells that are genetically engineered toexpress a protein or exhibit some other new behavior.

In the methods of the present invention, the SEC column may be anysuitable size and contain any SEC medium suitable for the separation ofa cyclodextrin or a cyclodextrin derivative from a protein. In oneembodiment, the SEC medium has a separation range from about 5-20 kDa toabout 75-300 kDa. The SEC medium may have a particle size of about 2 toabout 6 microns, preferably about 3-5 microns, e.g., about 4 microns.One example of a suitable SEC medium is TSK gel G2000 SW_(XL) (TosohBiosciences, Inc.). Another suitable SEC medium is a polymer-based TSKgel column. In a preferred embodiment, the separation is performed byhigh pressure liquid chromatography (HPLC). For HPLC, a suitable sizefor the SEC column is in the range of about 5 to about 15 mm in diameterand about 3 to about 60 cm in length. Sample sizes may be in the rangeof about 10 to about 500 μL, preferably about 50 to about 100 μL.

The sample to be loaded on the SEC column can be a sample from anysolution comprising a protein and for which it is desired to test forthe presence of a cyclodextrin or a cyclodextrin derivative. In oneembodiment of the invention, the sample is from a solution that containsa protein that is in the process of being purified or has been purifiedand in which it is desirable to determine the presence or quantity of acyclodextrin or a cyclodextrin derivative. In one embodiment the proteinhas been purified or is being purified from cells grown in cell culturein the presence of a cyclodextrin or a cyclodextrin derivative. Thesample may be from a solution at any stage of the purification processfor the protein, e.g., after cell lysis, after one or more purificationsteps (such as ion exchange chromatography, affinity chromatography,etc.), or after the final purification step. The protein in the solutionmay be at least 90% pure, preferably at least 95%, 96%, 97%, 98%, or 99%pure. In one embodiment, the sample is from a solution that has lessthan 20 μg/mL, preferably less than 10 μg/mL, 5 μg/mL, 2 μg/mL, or 1μg/mL of the cyclodextrin or cyclodextrin derivative.

The sample may be taken from the solution comprising the protein andloaded directly on the SEC column as long as the buffer of the solutionis suitable for SEC. If necessary, the buffer of the sample may beadjusted to be suitable for SEC. A suitable buffer for SEC is an aqueousbuffer having a pH between about 2.0 and about 8.0, preferably betweenabout 5.0 and about 7.5. Examples of suitable buffers include, but arenot limited to, sodium phosphate, potassium phosphate, sodium acetate,sodium citrate, potassium nitrate, and Tris-HCl. The buffer should alsocomprise sufficient salt to prevent the protein in the sample fromsticking to the column and the SEC medium. Suitable levels of salt arein the range of about 50 mM to about 300 mM, preferably about 100 mM toabout 200 mM, more preferably about 140 mM. Examples of salts that maybe used include, but are not limited to, sodium chloride, potassiumchloride, sodium sulfate, potassium sulfate, magnesium sulfate, ammoniumsulfate, ammonium phosphate, and magnesium chloride. Preferably the saltis sodium chloride.

In one embodiment of the invention, the sample does not undergo anypreparation steps other than adjustment of the buffer as necessary. Forexample, the sample is not extracted (e.g., with an organic solvent orwith a solid phase cartridge), dried, resuspended, concentrated, orotherwise altered. The ability to load samples directly on the SECcolumn, e.g., to test a pharmaceutical preparation at the point of fill,without complicated extractions or other manipulations (e.g., solvent orsolid phase extractions that could affect sample recovery) is one of theadvantages of the present invention.

The mobile phase may be an aqueous buffer having a pH between about 2.0and about 8.0, preferably between about 5.0 and about 7.5, andcomprising sufficient salt to prevent the protein in the sample fromsticking to the column or SEC medium (e.g., about 50 mM to about 300 mM,preferably about 100 mM to about 200 mM). Appropriate buffers and saltsare those listed above for sample preparation. One example of a suitablemobile phase is 140 mM NaCl, 10 mM phosphate, pH 6.45.

The agent that forms a detectable inclusion complex with a cyclodextrinor a cyclodextrin derivative may be brought into contact with anycyclodextrin or cyclodextrin derivative present in a sample before,during, or after the sample is separated by SEC. For example, the agentmay be added to a sample before it is loaded on the column, the agentmay be present in the mobile phase, the agent may be added to eluatefractions collected from the column, or any combination of the above. Ina preferred embodiment the agent is present in the mobile phase.

The agent is selected depending on the cyclodextrin or cyclodextrinderivative to be detected as different cyclodextrins have differentbinding specificities. Suitable agents are known in the art and may alsobe determined empirically for each cyclodextrin or cyclodextrinderivative. The agent may have an inherent detectable signal (e.g.,fluorescence) or may have a detectable label attached (e.g., afluorophore or radionuclide). In other embodiments, the agent may haveno inherent detectable signal but the inclusion complex formed when theagent binds to a cyclodextrin or cyclodextrin derivative produces adetectable signal. One example of a suitable fluorescent compound forthe detection of MBCD is 1-naphthol. Other examples of suitablefluorescent compounds include phenolphthalein and8-anilinonaphthalene-1-sulfonic acid. If the agent is water soluble itmay be added directly to the mobile phase. If the agent is not watersoluble it may be dissolved in an organic solvent, including, but notlimited to, methanol, ethanol, chloroform, or acetone, and added to themobile phase such that the percent of organic solvent is low (e.g., lessthan 10%, preferably less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%).The concentration of agent in the mobile phase is sufficient for asignal to be detected. For example, 1-naphthol or other fluorescentcompounds may be present in the mobile phase at a concentration of about1×10⁻⁸ to about 1×10⁻² M, preferably about 1×10⁻⁵ to about 1×10⁻³ M,preferably about 1×10⁻⁴ M.

The SEC separation may be performed by methods well known in the art,using suitable column preparation, sample loading, flow rate, fractioncollection, and signal detection techniques. See, for example,Deutscher, Meth. Enzymol.: Guide to Protein Purification, Vol. 182,Academic Press, Inc., San Diego (1990), Chapter 38; Balch et al., Meth.Enzymol., Vol. 257, Academic Press, Inc., San Diego (1995), Chapter 8);Scopes, Protein Purification: Principles and Practice, Springer-Verlag(1994); Sambrook et al., in Molecular Cloning: A Laboratory Manual;Ausubel et al., Current Protocols in Molecular Biology, eachincorporated by reference. In a preferred embodiment the separation isperformed by HPLC. The signal detector may be any detector useful forthe measurement of the agent, e.g., a fluorescence detector, anultraviolet detector, or a radiation detector, and may be used in linewith the column or separately. When a fluorophore is used as the agent,the fluorescent detector may be set at suitable excitation and emissionwavelengths as is known in the art, e.g., 290 nm and 360 nm,respectively, for 1-naphthol. When the cyclodextrin or cyclodextrinderivative is to be quantitated, the size of the detected signal may bemeasured and compared to a standard curve prepared from samples spikedwith increasing amounts of the agent in order to measure the amount ofcyclodextrin or cyclodextrin derivative present in the sample.

Using the methods of the invention, the limit of detection of acyclodextrin or a cyclodextrin derivative may be less than 100 μg/mL,preferably less than 50 μg/mL, 20 μg/mL, 10 μg/mL, 5 μg/mL, 2 μg/mL, or1 μg/mL.

Proteins, particularly therapeutic proteins, may be purified from cellcultures and prepared as pharmaceutical preparations. Cells may becultured in the presence of a cyclodextrin or a cyclodextrin derivative,particularly if the cells are dependent on a hydrophobic compound forgrowth, such as cholesterol auxotrophic cells (e.g., cholesterolauxotrophic derivatives of CHO, COS, or NSO cells). In one aspect of theinvention, pharmaceutical preparations may be evaluated for the presenceof a cyclodextrin or cyclodextrin derivative.

In the methods of the invention, any cell that is known in the art forprotein expression may be used. Examples include NSO cells, monkey COScells, Chinese Hamster Ovary (CHO) cells, human kidney 293 cells, humanepidermal A431 cells, human Colo205 cells, 3T3 coils, CV-1 cells, HeLacells, and mouse L cells, BHK, HL-60, U937, HaK or Jurkat cells. Cellsmay be cultured by any method known in the art. In one embodiment, thecells are cholesterol auxotrophic cells (e.g., NSO cells or cellsderived therefrom). In another embodiment, the cells are cultured in thepresence of MBCD. The cultured cells may naturally express the proteinto be purified or be genetically engineered to express the protein.Methods for genetically engineering cells to express a protein ofinterest are well known in the art. See, for example, Sambrook et al.,in Molecular Cloning: A Laboratory Manual; Ausubel et al., CurrentProtocols in Molecular Biology, each incorporated by reference. Thecells are cultured in the presence of the cyclodextrin or cyclodextrinderivative. The protein is then purified from the cultured cells or fromthe culture medium using techniques well known in the art, e.g., ionexchange chromatography, affinity chromatography, size exclusionchromatography, differential solubility, ultrafiltration, etc. Theprotein may be purified to at least 90% homogeneity, preferably at least95%, 96%, 97%, 98%, or 99% homogeneity. The purified protein is thencombined with a pharmaceutically acceptable carrier to produce apharmaceutical preparation.

Pharmaceutically acceptable carriers comprise excipients and additiveswhich facilitate processing of the protein into preparations that can beused pharmaceutically. Examples of excipients include, but are notlimited to, water, saline, phosphate buffered saline, dextrose,glycerol, ethanol, and the like. Additives that are well known in theart include, e.g., surfactants (e.g., TWEEN, such as TWEEN-80),detackifiers, anti-foaming agents, buffering agents, antioxidants (e.g.,ascorbyl palmitate, butyl hydroxy anisole (BHA), butyl hydroxy toluene(BHT) and tocopherols, e.g., α-tocopherol (vitamin E)), preservatives,chelating agents, thickening agents, fillers, binders, lubricants,viscomodulators, tonicifiers, flavorants, colorants, odorants,opacifiers, suspending agents, and plasticizers. Preferably, thepreparations are suitable solutions for administration by injection ororally and contain about 0.01 to about 99 percent, preferably about 0.25to about 75 percent of the protein together with the excipient.

The presence of a cyclodextrin or cyclodextrin derivative may bedetermined at any stage in the purification. In one embodiment, thepresence of a cyclodextrin or cyclodextrin derivative is determined inthe final pharmaceutical preparation. The method may further comprisemaking a record (e.g., a print or computer readable record, e.g., alabel) of the level of cyclodextrin or cyclodextrin derivative in asample, e.g., in a finally purified pharmaceutical preparation.

The following examples are illustrative, but not limiting, of the methodand compositions of the present invention. Other suitable modificationsand adaptations of the variety of conditions and parameters normallyencountered in chromatography and pharmaceutical preparation and,evaluation and which are obvious to those skilled in the art are withinthe spirit and scope of the invention.

Example 1

Natilizumab was recombinantly expressed in cholesterol auxotrophic cellscultured in the presence of about 720 mg/L MBCD. The antibody waspurified in three routine chromatographic steps. A method fordetermining the amount of MBCD present after each of the purificationsteps and in the final antibody preparation (suitable for pharmaceuticaluse) was developed.

Samples were separated by HPLC on an SEC column (TSK gel G2000SW_(XL),7.8 mm×30 cm). The mobile phase contained 140 mM NaCl, 10 mM phosphate,pH 6.45/2% (v/v) methanol and 10⁻⁴ M 1-naphthol. Sample sizes were 50 μL(Waters fluorescence detector) or 100 μL (Rainin fluorescence detector).The flow rate was 1 mL/minute under isocratic conditions. TheMBCD/1-naphthol inclusion complex was detected using a fluorescencedetector at 290 and 360 nm for excitation and emission, respectively.

Limit of detection assays were performed using serial dilution of a MBCDstandard (1.0 mg/mL MBCD in water) in an aqueous buffer at pH 6.1. Usingthis technique the limit of detection was determined to be 1.3 μg/mL.Similar assays were performed to determine the limit of detection insamples of eluate from each of the three chromatographic columns and thefinal purified antibody preparation. The limit of detection in thesamples was very low, ranging from 1.3 μg/mL to 5.2 μg/mL, with anaverage of 3.0 μg/mL. Representative chromatograms are shown in FIG. 1.

In order to assess the linearity of the assay, five standards containing1.3, 2.6, 10, 26, and 65 μg/mL MBCD were injected onto the HPLC columnin a volume of 50 μL. The linear least square regression is shown inFIG. 2. The results indicate that the assay has high linearity, with acorrelation coefficient of 0.998.

The linearity was also investigated using samples of the final antibodypreparation spiked with 1.3, 2.6, 5.0, 10.0, 20.0, and 50.0 μg/mL MBCD.The results (FIG. 3) show that the assay has high linearity, with acorrelation coefficient of 0.999.

The recovery of MBCD in the final antibody preparation was calculated bycomparing the peak areas to those of the corresponding MBCD standard. Assummarized in Table 1, the recoveries were between 97% and 117% for theMBCD concentrations tested.

TABLE 1 Concentration MBCD Observed Recovery (μg/mL) (μg/mL) (Average, n= 2) (%) 1.3 1.4 112 2.6 3.0 117 5.0 4.9 98 10.0 9.7 97 20.0 21 104 50.052 103

The relative standard deviation for repeatability (intra-assayprecision) was determined using five standards containing 1.3, 2.6, 10,26, and 65 μg/mL MBCD. The results are shown in Table 2 and indicatethat the assay has a relative standard deviation of less than 5.0%.

TABLE 2 MBCD Observed Values Standard Deviation Percent RSD (μg/mL)(μg/mL) (n = 5) (n = 5) (n = 5) 1.3 2.1 0.1 4.7 2.6 3.1 0.1 3.2 10 9.60.2 2.1 26 24.6 1.1 4.4 65 65.6 2.0 3.1

Having now fully described the invention, it will be understood by thoseof ordinary skill in the art that the same can be performed within awide and equivalent range of conditions, formulations and otherparameters without affecting the scope of the invention or anyembodiment thereof. All patents, patent applications and publicationscited herein are fully incorporated by reference herein in theirentirety.

1-66. (canceled)
 67. A method for recovering a cyclodextrin orcyclodextrin derivative from a solution comprising a proteinrecombinantly expressed in the presence of the cyclodextrin orcyclodextrin derivative, the method comprising loading the solution on asize exclusion chromatography (SEC) column, wherein the solution doesnot undergo a step of extraction prior to being loaded on the SECcolumn; separating the cyclodextrin or cyclodextrin derivative from therecombinantly expressed protein by SEC; contacting the cyclodextrin orcyclodextrin derivative with an agent that forms a detectable inclusioncomplex with the separated cyclodextrin or cyclodextrin derivative; andmeasuring the amount of a signal from the inclusion complex, wherein thesignal is indicative of the quantity of the cyclodextrin or cyclodextrinderivative recovered from the solution.
 68. The method of claim 67,wherein the cyclodextrin or cyclodextrin derivative ismethyl-β-cyclodextrin.
 69. The method of claim 67, wherein therecombinantly expressed protein is an antibody.
 70. The method of claim67, wherein the solution is a pharmaceutical preparation.
 71. The methodof claim 67, wherein the solution comprises less than 20 μg/mL of thecyclodextrin or cyclodextrin derivative.
 72. The method of claim 67,wherein the agent is a fluorescent compound.
 73. The method of claim 72,wherein the agent is 1-naphthol.
 74. The method of claim 67, wherein themethod has a cyclodextrin or a cyclodextrin derivative limit ofdetection of less than 10 μg/mL.
 75. The method of claim 74, wherein themethod has a cyclodextrin or a cyclodextrin derivative limit ofdetection of less than 2 μg/mL.
 76. The method of claim 67, wherein theSEC column has a separation range of about 5-20 kDa to about 75-300 kDa.77. The method of claim 67, wherein the SEC column has a particle sizeof about 2 to about 6 microns.
 78. The method of claim 77, wherein theSEC column has a particle size of about 4 microns.
 79. The method ofclaim 67, wherein at least 97%±5% of the cyclodextrin or cyclodextrinderivative is recovered.
 80. The method of claim 67, wherein theseparation uses a mobile phase comprising a salt at a concentration ofabout 50 mM to about 300 mM.
 81. The method of claim 80, wherein thesolution and the mobile phase have a pH of about 2.0 to about 8.0. 82.The method of claim 81, wherein the solution and the mobile phase have apH of about 5.0 to about 7.5.
 83. The method of claim 80, wherein theagent is present in the mobile phase during the separating step.
 84. Themethod of claim 67, wherein the recombinantly expressed protein is atleast 90% pure.
 85. The method of claim 84, wherein the recombinantlyexpressed protein is at least 95% pure.
 86. The method of claim 85,wherein the recombinantly expressed protein is at least 98% pure.